System and method for treatment of spent caustic wastewater

Abstract

The present disclosure relates to a process for treating and regenerating a spent caustic solution at ambient temperatures and pressure which includes oxidizing spent caustic wastewater with a brine solution and ozone mixture, supported by irradiation of the spent caustic wastewater by ultrasound. A range of wastewater treatment techniques may also be included to reach a desired effluent quality level.

What is claimed is: 
     
       1. A system for treating spent caustic wastewater comprising:
 a treatment system including:
 a brine mixture and oxygen treatment apparatus configured to mix a brine mixture and ozone with the spent caustic wastewater, wherein the spent caustic wastewater comprises greater than 10 ppm total sulfide content; 
 a pH adjustment apparatus configured to mix acid with the spent caustic wastewater; and 
 an agitator for providing a mechanical catalyst to an output of the oxygen treatment apparatus; and 
 
 an ultrasound apparatus to assist in accelerating chemical reactions between the spent caustic wastewater, the brine mixture and ozone; 
 wherein the combination of the brine mixture, ozone and spent caustic wastewater and the mechanical catalyst produce a treated wastewater, wherein the treated wastewater comprises less than 10 ppm total sulfide content; 
 wherein the brine mixture is a combination of a halogen and an alkaline component; and 
 wherein the alkaline component is ammonia (NH 3 ). 
 
     
     
       2. The system of  claim 1  wherein the halogen is selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I). 
     
     
       3. The system of  claim 1  further comprising a coolant pump for cooling the treated wastewater. 
     
     
       4. The system of  claim 1  further comprising:
 a wastewater tank, connected to an input of the treatment system, for holding the spent caustic wastewater; and 
 a holding tank, connected to an output of the treatment system, for holding the treated wastewater. 
 
     
     
       5. The system of  claim 4  further comprising a pump for pumping the spent caustic wastewater from the wastewater tank to the holding tank. 
     
     
       6. The system of  claim 5  further comprising:
 a brine mixture tank for storing the brine mixture for use by the brine mixture and ozone treatment apparatus; 
 an oxygen generator for storing ozone for use by the brine mixture and oxygen treatment apparatus; and 
 an acid tank for storing acid for use by the pH adjustment apparatus. 
 
     
     
       7. A method of treating spent caustic wastewater comprising:
 mixing a halogen with an alkaline component to produce a brine mixture; 
 mixing the brine mixture with the spent caustic wastewater wherein the spent caustic wastewater comprises greater than 10 ppm total sulfide content; 
 adding ozone to the spent caustic wastewater; 
 applying a mechanical catalyst to a combination of the brine mixture, ozone and the spent caustic wastewater; and 
 applying an ultrasound cavitation to the combination of the brine mixture, ozone and the spent caustic wastewater to produce a treated wastewater, wherein the treated wastewater comprises less than 10 ppm total sulfide content; 
 wherein the alkaline component is ammonia (NH 3 ). 
 
     
     
       8. The method of  claim 7  further comprising:
 adding an acid to balance a pH of the combination to produce a treated wastewater. 
 
     
     
       9. The method of  claim 8  wherein the halogen is selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I). 
     
     
       10. The method of  claim 7  wherein the brine mixture and the ozone are mixed together before being added to the spent caustic wastewater. 
     
     
       11. The method of  claim 7  wherein the brine mixture and the ozone are added to the spent caustic wastewater concurrently.